Wounds are internal or external bodily injuries or lesions caused by mechanical, chemical, viral, bacterial or thermal means, which disrupt the normal continuity of structures. Such bodily injuries include contusions, which are wounds in which the skin is unbroken, incisions, i.e., wounds in which the skin is broken by a cutting instrument, and lacerations, which are wounds in which the skin is broken by a dull or blunt instrument. Patients who suffer major wounds could benefit from an antiscarring wound healer enhancer, that protects and enhances repair while reducing the pain, swelling, tissue ischemia, excess angiogenesis, erythema (redness), crusting, itching, and fibrotic conditions (scarring) which accompany most wounds.
Wound healing consists of a series of processes whereby injured tissues are repaired, specialized tissue is generated, and new tissue is reorganized. Wound healing consists of three major phases: (a) an inflammation phase (0–3 days), (b) a cellular proliferation phase (3–12 days), and (c) a remodeling phase (3–6 months).
During the inflammation phase, platelet aggregation and clotting form a matrix which traps plasma proteins and blood cells to induce the influx of various types of cells. During the cellular proliferation phase, new connective or granulation tissue and blood vessels are formed. During the remodeling phase, granulation tissue is replaced by a network of collagen and elastin fibers leading to the formation of scar tissue. Most wounds also produce pain, swelling, itching, ischemia, crusting, erythema, and scarring, all of which are undesirable.
When cells are injured or killed as a result of a wound, a wound-healing step is desirable to resuscitate the injured cells and produce new cells to replace the dead cells. The healing process requires the reversal of cytotoxicity, the suppression of inflammation, the stimulation of cellular viability and proliferation and reduced scarring. Wounds require low levels of oxygen in the initial stages of healing to suppress oxidative damage and higher levels of oxygen in the later stages of healing to promote collagen formation by fibroblasts.
Wounds produce oxygen radicals. Mammalian cells are continuously exposed to activated oxygen species such as superoxide (O2—), hydrogen peroxide (H2O2), hydroxyl radicals (OH), and singlet oxygen (1O2). In vivo, these reactive oxygen intermediates are generated by cells in response to aerobic metabolism, catabolism of drugs and other xenobiotics, ultraviolet and x-ray radiation, and the respiratory burst of phagocytic cells (such as white blood cells) to kill invading bacteria introduced through wounds. Hydrogen peroxide, for example, is produced during respiration of most living organisms especially by stressed and injured cells.
These active oxygen species can injure cells. An important example of such damage is lipid peroxidation which involves the oxidative degradation of unsaturated lipids. Lipid peroxidation is highly detrimental to membrane structure and function and can cause numerous cytopathological effects. Cells defend against lipid peroxidation by producing radical scavengers such as superoxide dismutase, catalase, and peroxidase. Injured cells have a decreased ability to produce radical scavengers. Excess hydrogen peroxide can react with DNA to cause backbone breakage of the DNA, produce mutations, as well as the alteration and liberation of the bases. Hydrogen peroxide can also react with pyrimidines to open the 5,6-double bond, which inhibits the ability of pyrimidines to hydrogen bond to complementary bases, Hallaender, et al. (1971). Such oxidative biochemical injury can result in the loss of cellular membrane integrity, reduced enzyme activity, changes in transport kinetics, changes in membrane lipid content, and leakage of potassium ions, amino acids, other cellular material, and the formation of excess keloid and scar formation.
Inflammation is a nonspecific response caused by a variety of injuries including the penetration of the host by an infectious agent. The distinguishing feature of inflammation is the dilation and increased permeability of minute blood vessels. The inflammatory response consists of three successive phases: (a) increased vascular permeability with resulting edema, pain, and swelling, (b) cellular infiltration and phagocytoses, and (c) proliferation of the fibroblasts synthesizing new connective tissue to repair the injury. A large number of mediators of inflammation have been implicated in the inflammatory process primarily in terms of their capacity to induce vasodilatation and increased permeability. Inflammation also increases levels of compounds that increase pain, erythema, ischemia, excess angiogenesis, swelling, crusting, itching, and scarring.
Direct injury, such as that caused by toxins produced by microorganisms, leads to destruction of vascular endothelium and results in the increased permeability to plasma proteins, especially in the venules and venular capillaries. Mediators of secondary injury are liberated from the site of direct injury. As a result, gaps form between vascular endothelial cells through which plasma proteins escape. Granulocytes, monocytes, and erythrocytes may also leave vascular channels. Mediators of secondary injury include unknown substances and histamine, peptides (kinins), kinin-forming enzymes (kininogenases), and a globulin permeability factor. These mediators are blocked from action by antihistamines and sympathoamines, and are most pronounced in effect on venules, although lymph-vascular endothelium also becomes more porous as a part of secondary injury. In the early stages of inflammation, the exudate is alkaline and neutrophilic polymorphonuclear leukocytes predominate. As lactic acid accumulates, presumably from glycolysis, the pH drops and macrophages become the predominant cell type. Lactic acid and antibodies in the inflammatory exudate may inhibit parasites, but the major anti-infectious effect of the inflammatory response is attributable to phagocytic cells.
The beneficial effect of the inflammatory response is the production of:    (1) leukocytes in great numbers; (2) plasma proteins, nonspecific and specific humoral agents, fibrinogen that on conversion to fibrin aids in the localization of the infectious process while acting as a matrix for phagocytoses; and (3) increased blood and lymph flow that dilutes and flushes toxic materials while causing a local increase in temperature.
The initial increase in capillary permeability and vasodilatation in an inflamed wound is followed by an increase in metabolism of the tissues. Leakage of fibrinogen into the wound, where proteolytic enzymes convert it into fibrin thrombi, establishes a capillary and lymphatic blockade. The concentrations of components of the ground substance of connective tissue collagen, mucopolysaccharides, glycoproteins, and nonfibrous proteins are greatly increased during this process. As the exudative phase of the inflammation subsides, the fibroblast is found to be the dominant cell in the wounded zone. The fibroblast first proliferates, then synthesizes extracellular material, including new collagen fibers and acid mucopolysaccharides, which are laid down to form the new tissue matrix.
On a macroscopic level, the inflammatory phenomenon is usually accompanied by the familiar clinical signs of erythema, swelling, edema tenderness (hyperalgesia), and pain. During this complex response, chemical mediators such as histamine, 5-hydroxytryptamine (5-HT), slow-reacting substance of anaphylaxis (SRS-A), various chemotactic factors, bradykinin, and prostaglandins are liberated locally. Phagocytic cells migrate into the area, and cellular lysosomal membranes may be ruptured, releasing lytic enzymes. All these events may contribute to the inflammatory response.
The production of reactive oxygen intermediates has been suggested to cause many skin, tissue, and organ disorders such as atherosclerosis, arthritis, cytotoxicity, skin inflammation, photoaging, wrinkling, actinic keratosis, tumor formation, cancer, hypertension, Parkinson's Disease, lung disease, and heart disease. The role of active oxygen radicals in promoting tumors has been based on the findings that (a) tumor promoters increase the level of oxygen radicals, (b) many free radical-generating systems promote tumors, and (c) certain antioxidants inhibit the biochemical effects of tumor promoters.
In vitro, reactive oxygen intermediates can be generated in cellular culture media by auto-oxidation and photo-oxidation of media components. During excision and storage, transplant organs can suffer oxidative injuries which result in the loss of cellular membrane integrity and shorten the usable life of the organ.
When cells are stressed by oxidative injury, a resuscitation step is necessary to re-condition the cells. Antioxidants have been shown to inhibit damage associated with active oxygen species. For example, pyruvate and other alpha-keto acids have been reported to react rapidly and stoichiometrically with hydrogen peroxide to protect cells from adverse cytolytic effects, O'Donnell-Tormey, et al., J. Exp. Med., 165, pp. 500–514 (1987).
U.S. Pat. No. 5,210,098, issued to Nath disclose a method to arrest or prevent acute kidney failure by administration of a non-toxic pyruvate salt to a patient in need of such treatment.
The Nath '098 invention provides a therapeutic method comprising the administration of an amount of a pyruvate salt to a patient experiencing or in danger of, acute renal failure. The pyruvate salt, preferably sodium pyruvate, is dispersed or dissolved in a pharmaceutically acceptable liquid carrier and administered parenterally in an amount effective to arrest or prevent said acute renal failure, thus permitting restoration of normal kidney function. In some cases, the pyruvate may be infused directly into the kidney or into the proximal renal arterial circulation. The method is effective to prevent or counter-act acute kidney failure due to a wide variety of causes, including, but not limited to, traumatic injury including burn injury and obstruction; reperfusion following ischemia, inflammatory glomerulonephritis, and sepis, e.g., due to gram negative bacterial infection.
U.S. Pat. No. 5,296,370, issued to Martin, et al. 1994, discloses therapeutic compositions for preventing and reducing injury to mammalian cells and increasing the resuscitation rate of injured mammalian cells. In one embodiment, the therapeutic composition comprises (a) a pyruvate selected from the group consisting of pyruvic acid, pharmaceutically acceptable salts of pyruvic acid, and mixtures thereof, (b) an antioxidant, and (c) a mixture of saturated and unsaturated fatty acids wherein the fatty acids are those fatty acids required for the resuscitation of injured mammalian cells.
U.S. Pat. No. 5,256,697, issued to Miller, et al., discloses a method for orally administering a therapeutically effective amount of a pyruvate precursor to a mammal to improve insulin resistance, lower lasting insulin levels and reduce fat gain.
U.S. Pat. Nos. 3,920,835; 3,984,556, and 3,988,470, all issued to Van Scott, et al. disclose methods for treating acne, dandruff, and palmar keratosis, respectively, which consist of applying to the affected area a topical composition comprising from about 1% to about 20% of a lower aliphatic compound containing from two to six carbon atoms selected from the group consisting of alpha-hydroxy acids, alpha-keto acids and esters thereof, and 3-hydroxybutryic acid in a pharmaceutically acceptable carrier. The aliphatic compounds include pyruvic acid and lactic acid.
U.S. Pat. Nos. 4,105,783 and 4,197,316, both issued to Yu, et al., disclose a method and composition, respectively, for treating dry skin which consists of applying to the affected area a topical composition comprising from about 1% to about 20% of a compound selected from the group consisting of amides and ammonium salts of alpha-hydroxy acids, beta-hydroxy acids, and alpha-keto acids in a pharmaceutically acceptable carrier. The compounds include the amides and ammonium salts of pyruvic acid and lactic acid.
U.S. Pat. No. 4,234,599, issued to Van Scott, et al., discloses a method for treating actinic and non-actinic skin keratoses which consists of applying to the affected area a topical composition comprising an effective amount of a compound selected from the group consisting of alpha-hydroxy acids, beta-hydroxy acids, and alpha-keto acids in a pharmaceutically acceptable carrier. The acidic compounds include pyruvic acid and lactic acid.
U.S. Pat. No. 4,294,852, issued to Wildnauer, et al., discloses a composition for treating skin which comprises the alpha-hydroxy acids, beta-hydroxy acids, and alpha-keto acids disclosed above in combination with C3–C8 aliphatic alcohols.
U.S. Pat. No. 4,663,166, issued to Veech, discloses an electrolyte solution which comprises a mixture of L-lactate and pyruvate in a ratio from 20:1 to 1:1, respectively, or a mixture of D-beta-hydroxybutyrate and acetoacetate, in a ratio from 6:1 to 0.5:1, respectively.
Sodium pyruvate has been reported to reduce the number of erosions, ulcers, and hemorrhages on the gastric mucosa in guinea pigs and rats caused by acetylsalicylic acid. The analgesic and antipyretic properties of acetylsalicylic acid were not impaired by sodium pyruvate, Puschmann, Arzneimittelforschung, 33, pp. 410–415 and 415–416 (1983).
Pyruvate has been reported to exert a positive inotropic effect in stunned myocardium which is a prolonged ventricular dysfunction following brief periods of coronary artery occlusions which does not produce irreversible damage, Mentzer, et al., Ann. Surg., 209, pp. 629–633 (1989). Pyruvate has also been reported to produce a relative stabilization of left ventricular pressure and heart work parameter and to reduce the size of infarctions. Pyruvate improves resumption of spontaneous beating of the heart and restoration of normal rates and blood pressure development, Bunger, et al., J. Mol. Cell. Cardiol., 18, pp. 423–438 (1986), Mochizuki, et al., J. Physiol. (Paris), 76, pp. 805–812 (1980), Regitz, et al., Cardiovasc. Res., 15 pp. 652–658 (1981), Giannelli, et al., Ann. Thorac. Surg., 21 pp. 386–396 (1976).
Sodium pyruvate has been reported to act as an antagonist to cyanide intoxication (presumably through the formation of cyanohydrin) and to protect against the lethal effects of sodium sulfide and to retard the onset and development of functional, morphological, and biochemical measures of acrylamide neuropathy of axons, Schwartz, et al., Toxicol. Appl. Pharmacol., 50 pp. 437–442 (1979), Sabri, et al., Brain Res., 483, pp. 1–11 (1989).
U.S. Pat. No. 5,798,388, issued to Katz discloses a method and compositions for the treatment of pulmonary diseases resulting from inflammation consisting of the administration of pyruvate, lactate, and precursor thereof and their salts in a pharmaceutically acceptable carrier. The compositions may also be a cellular energy source.
A chemotherapeutic cure of advanced L1210 leukemia has been reported using sodium pyruvate to restore abnormally deformed red blood cells to normal. The deformed red blood cells prevented adequate drug delivery to tumor cells, Cohen, Cancer Chemother. Pharmacol., 5, pp. 175–179 (1981).
Primary cultures of heterotopic tracheal transplant exposed in vivo to 7,12-dimethylbenz(a)anthracene were reported to be successfully maintained in enrichment medium supplemented with sodium pyruvate along with the cultures of interleukin-2 stimulated peripheral blood lymphocytes, and plasmacytomas and hybridomas, pig embryos, and human blastocysts, Shacter, J. Immunol, Methods, 99, pp. 259–270 (1987), Marchok, et al., Cancer Res., 37, pp. 1811–1821 (1977), Davis, J. Reprod. Fertil, Suppl., 33, pp. 115–124 (1985), Okamoto, et al., No To Shinkei, 38, pp. 593–598 (1986), Cohen, et al., J. In vitro Fert. Embryo Transfer, 2, pp. 59–64 (1985).
U.S. Pat. Nos. 4,158,057; 4,351,835; 4,415,576, and 4,645,764, all issued to Stanko, disclose methods for preventing the accumulation of fat in the liver of a mammal due to the ingestion of alcohol, for controlling weight in a mammal, for inhibiting body fat while increasing protein concentration in a mammal, and for controlling the deposition of body fat in a living being, respectively. The methods comprise administering to the mammal a therapeutic mixture of pyruvate and dihydroxyacetone, and optionally riboflavin. U.S. Pat. No. 4,548,937, issued to Stanko, discloses a method for controlling the weight gain of a mammal which comprises administering to the mammal a therapeutically effective amount of pyruvate, and optionally riboflavin. U.S. Pat. No. 4,812,479, issued to Stanko, discloses a method for controlling the weight gain of a mammal which comprises administering to the mammal a therapeutically effective amount of dihydroxyacetone, and optionally riboflavin and pyruvate.
Rats fed a calcium-oxalate lithogenic diet including sodium pyruvate were reported to develop fewer urinary calculi (stones) than control rats not given sodium pyruvate, Ogawa, et al., Hinvokika Kivo, 32, pp. 1341–1347 (1986).
U.S. Pat. No. 4,521,375, issued to Houlsby, discloses a method for sterilizing surfaces which come into contact with living tissue. The method comprises sterilizing the surface with aqueous hydrogen peroxide and then neutralizing the surface with pyruvic acid.
U.S. Pat. No. 4,416,982, issued to Tauda, et al., discloses a method for decomposing hydrogen peroxide by reacting the hydrogen peroxide with a phenol or aniline derivative in the presence of peroxidase. U.S. Pat. No. 4,696,917, issued to Lindstrom, et al., discloses an irrigation solution which comprises Eagle's Minimum Essential Medium with Earle's salts, chondroitin sulfate, a buffer solution, 2-mercaptoethanol, and a pyruvate. The irrigation solution may optionally contain ascorbic acid and alpha-tocopherol. U.S. Pat. No. 4,725,586, also issued to Lindstrom, et al., discloses an irrigation solution which comprises a balanced salt solution, chondroitin sulfate, a buffer solution, 2-mercaptoethanol, sodium bicarbonate or dextrose, a pyruvate, a sodium phosphate buffer system, and cystine. The irrigation solution may optionally contain ascorbic acid and gammatocopherol.
U.S. Pat. No. 4,847,069, issued to Bissett, et al., discloses a photoprotective composition comprising (a) a sorbohydroxamic acid, (b) an anti-inflammatory agent selected from steroidal anti-inflammatory agents and a natural anti-inflammatory agent, and (c) a topical carrier. Fatty acids may be present as an emollient. U.S. Pat. No. 4,847,071, also issued to Bissett, et al., discloses a photoprotective composition comprising (a) a tocopherol or tocopherol-ester radical scavenger, (b) an anti-inflammatory agent, and (c) a topical carrier. U.S. Pat. No. 4,847,072, issued to Bissett, et al., discloses a topical composition comprising not more than 25% tocopherol sorbate in a topical carrier.
U.S. Pat. No. 5,863,938, issued to Martin, discloses a therapeutic antibacterial wound-healing composition comprising an effective amount of an antibacterial agent and a wound-healing composition consisting of (a) pyruvate- or keto-glutaric acid (b) an antioxidant, and (c) a mixture of fatty acids.
U.S. Pat. No. 5,561,157, issued to Yu, et al., discloses a composition and method for the therapeutic treatment of age spots, wrinkles, dry skin, eczema, psoriasis, and keratosis, using alpha- and beta-keto-carboxylic acids and their salts.
U.S. Pat. No. 6,149, 924, issued to Paul discloses the use of many agents that increase the production of skin lipids, increase barrier function, hydrogen peroxide neutralization, prevention of loss of moisturizing factor from the skin. The agents are amino acids and their breakdown products.
U.S. Pat. No. 5,536,751, issued to Bunger discloses a pharmaceutical composition as an active phosphorylation potential enhancing substance using an alpha-keto-carboxylic acid, primarily pyruvate.
The addition of sodium pyruvate to bacterial and yeast systems has been reported to inhibit hydrogen peroxide production, enhance growth, and protect the systems against the toxicity of reactive oxygen intermediates. The optimum ratio of unsaturated to saturated fatty acids contained within chicken fat enhanced membrane repair and reduced cytotoxicity. The anti-oxidants gluthathione and thio-glycollate reduced the injury induced by oxygen radical species.
While the above therapeutic compositions and methods are reported to inhibit the production of reactive oxygen intermediates and enhance healing, none of the compositions and methods treat the damage and resulting disease state in mammals caused by undesired pain, progressive tissue ischemia, excess angiogenesis, excess white blood cell (WBC) infiltration, erythema, swelling, itching, crusting, and scarring. Moreover, cellular signaling agents in mammalian cells are needed to deposit the correct ratio and type of collagen and elastin. The new teachings involve the use of alpha-keto acids with unique properties, singly or in combination to treat different types of injuries.